1. Field of the Invention
The invention relates to anchors for attaching soft tissue to bone. More particularly, the invention relates to apparatus and methods related to inserting suture anchors in bone in order to attach soft tissue thereto.
2. Description of the Prior Art
In the course of certain surgical procedures, soft tissue is secured to a selected bone surface either directly, via some type of implant, or indirectly via an implant (i.e. an anchor) to which suture is attached, the suture then being tied to the soft tissue to hold it in place. Anchors may be used to attach soft tissue such as ligaments, tendons, muscles, etc. to a surface from which the soft tissue has become detached and may also be used to secure soft tissue to supplementary attachment sites for reinforcement. For example, in urological applications anchors may be used in bladder neck suspensions to attach a portion of the bladder to an adjacent bone surface. Such soft tissue attachment may be done during either open or closed surgical procedures, the latter being generally referred to as arthroscopic or endoscopic surgery. The terms "arthroscopic" and "endoscopic" may be used interchangeably herein and are intended to encompass arthroscopic, endoscopic, laparoscopic, hysteroscopic or any other similar surgical procedures performed with elongated instruments inserted through small openings in the body.
In procedures requiring suturing of soft tissue to bone, the suture may either be first anchored by so-called suture anchors to the bone before passing the suture through the soft tissue, or the tissue may first be sutured and the anchor may then be slid down one leg of the suture and then implanted into bone. The prior art includes numerous types of suture anchors adapted to be secured in the bone, sometimes directly in one step and sometimes in pre-drilled holes or tunnels. The term "suture anchor" is used broadly and will be understood to refer to devices having a similar structure even if material other than suture is connected to the device. Some prior art suture anchors are elongated and have annular ribs or radially extending barbs and are required to be pushed or hammered directly into bone or into a pre-formed bone tunnel (exemplified by U.S. Pat. Nos. 5,102,421 (Anspach, Jr.); 5,141,520 (Goble et al.); 5,100,417 (Cerier et al.); 5,224,946 (Hayhurst et al.) and 5,261,914 (Warren)). Pushing an anchor into place has the disadvantage of potential trauma and damage to surrounding bone tissue, and has limited applicability where the location of the bone tunnel or pre-drilled hole is not axially aligned with an arthroscopic portal to permit transmission of the impacting force through an impactor to the anchor. An impacted suture anchor is not easily removable without damaging the bone into which it has been placed. Consequently, threaded suture anchors are often used as exemplified by U.S. Pat. Nos. 5,156,616 (Meadows et al.) and 4,632,100 (Somers et al.). Depending upon the type of threaded anchor, the insertion procedure may enable direct threading of the anchor into the bone or it may sometimes require that a pilot hole first be drilled into the bone, the hole then either enabling an anchor to be screwed in or enabling threads to be tapped to receive the anchor.
Devices used to insert suture anchors into bone surfaces provide an interface between the actual implant and the surgeon performing the procedure. While this interface is most important in endoscopic surgical procedures because of the limited accessibility of the surgical site, prior art endoscopic procedures generally utilize devices and methods designed for open surgical procedures. All known procedures used to insert suture anchors endoscopically rely on elongated extensions which pass through the portals or cannulas used in the procedures. Similar elongated extensions are also used in open procedures. With respect to non-threaded or non-turnable suture anchors, these extensions merely are required to transmit longitudinal forces from the proximal end to the distal end where the suture anchor is situated. With respect to turnable or threaded suture anchors, the inserting device must be elongated as well as strong enough to transmit sufficient torque from the proximal end to the distal tip to turn the anchor.
Threaded suture anchors are preferably inserted into the bone surface so that the proximal end of the anchor lies at or beneath the bone surface in order not to injure the soft tissue which is intended to be approximated to the bone surface. Consequently, the inserting device must be able to countersink the anchor a sufficient degree. Furthermore, known suture anchors are inserted with the suture already joined to the anchor so the anchor driver must, therefore, accommodate suture while it is turning.
A known threaded anchor inserting device is used to drive a threaded anchor of the type shown in aforementioned U.S. Pat. No. 4,632,100 (Somers et al.), incorporated herein by reference. The anchor is known as the STATAK.TM. soft tissue attachment device, available from the assignee hereof, and is premounted with suture in a disposable driver which fits any standard cannulated drill. The driver is an elongated hollow tube having a drive recess at its distal end for engaging a corresponding drive surface on the anchor (FIG. 1). The driver has an annular shoulder near its distal end, proximal to the drive recess in order to abut the bone surface at the site of implantation of the anchor. When the driver is turned, the threaded anchor advances into the bone (FIGS. 2 and 3) and, after the shoulder abuts the bone, the driver continues to turn to advance the anchor further to assure that its proximal end becomes countersunk (FIG. 4). The driver includes an automatic release feature to disengage from the anchor when it is properly positioned. This feature causes the anchor to automatically stop advancing and turning when it reaches a predetermined depth below the bone surface, that depth being defined at the point where its driver portion advances beyond the distal tip of the driver. Removal of the driver deploys the suture which was arrayed inside.
While in open procedures the anchor and driver assembly may be directly used as described above, in endoscopic procedures the anchor and driver assembly must first be inserted through a portal or cannula to position the anchor at the implantation site. Preferably, a cannula is used to avoid injuring tissue with the anchor. The internal diameter of the cannula must be large enough to pass the driver. The shoulder at the distal end of the driver necessitates the use of a large diameter cannula. Furthermore, in order to minimize trauma to the patient and facilitate the use of suture anchors at certain sites, a cannulated drill guide is necessary to hold the driver in place as it is turned. Using such a drill guide in addition to the known driver necessitates the use of a still larger cannula in order to enable the suture anchor to be properly used endoscopically. Because of the limited visibility available in endoscopic procedures, it is always desirable to minimize the size of the instrumentation as much as possible. This decrease in size improves visualization and enables the use of endoscopic instruments in small confined spaces. It would be desirable to produce a smaller diameter driver than presently known so that smaller cannulae could be used to minimize the size of the required portal and also to facilitate anchor use in certain small, confined locations (shoulder, etc.).
Additionally, insertion of threaded suture anchors in some situations may be improved if the anchor could be inserted to varying depths. It would be desirable, therefore, to produce a driver capable of inserting an anchor to different depths.
Prior art anchor drivers of the type having a distal shoulder are only suitable for driving the threaded anchor into place. Once the anchor advances beyond the tip of the drive shaft, the anchor is no longer reachable with the driver and, if one desires to remove the anchor, a separate instrument must be used. It may in some instances be desirable to remove the anchor and having a driver which could serve as a remover could be helpful in certain situations.
It is accordingly an object of this invention to produce a system for inserting threaded suture anchors.
It is also an object of this invention to produce a driving system capable of countersinking a threaded suture anchor while minimizing the diameter of the driver.
It is another object of this invention to produce a driving system capable of countersinking a threaded suture anchor to varying depths.
It is an additional object of this invention to produce a driving system for inserting threaded suture anchors which is smaller than known systems in order to improve visualization and provide greater access to confined spaces.
It is also an object of this invention to produce a driver which can also be used for removal of a threaded suture anchor while also enabling countersinking of the suture anchor upon insertion.